Various control systems have been provided heretofore for the operation of direct-current motors and some of these circuits can include elements intended for automatic braking of rotation of the motor upon de-energization. Such systems can be used for practically any motor-control purposes and generally comprise a thyristor, controlled rectifier or other circuit element which is switched between a blocking and an unblocking state by transistors, diode networks or the like.
Many of these systems are relatively complicated and cannot effectively be used for current-limiting operations without additional circuit elements.